JPH0261379B2 - - Google Patents

Abstract

What is disclosed is a method for making a gastight multiple-walled panel of extruded resin from an integrally extruded hollow panel comprising two parallel, plane outer walls having supporting partitions disposed between them and defining long hollow cells with open end faces, which method comprises heating the hollow panel at least in the area of the open end faces of said hollow cells until the resin is in the thermoplastic state, and then heat sealing the two outer walls in the thermoplastic area thereof in a gastight manner either to each other or to a tape of a further thermoplastic material covering the end faces, the seal so produced being held for at least 1 minute at a temperature ranging from 10 DEG C. beneath the Vicat softening point to 20 DEG C. above the Vicat softening point of the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an integrally extruded body comprising two generally flat, parallel outer walls and a belly plate disposed between the two outer walls, joining the two outer walls, and extruded together with the outer walls. The present invention relates to a method for manufacturing a gas-tight closed cavity board of extruded plastic, starting from a hollow profiled board, and having a number of cavities contained between the two outer walls and the belly plate. The outer wall and the belly plate are integrally extruded from thermoplastic, preferably translucent, especially transparent plastic. The ventral plate may be at an angle of inclination to both outer walls, but is preferably arranged perpendicularly. Also, the ventral plate is inside the hollow chamber plate,
They may also be connected to each other by an additional intermediate wall, which is preferably arranged parallel to the outer wall.

This type of extruded hollow chamber board is used on a large scale for glazing greenhouses, indoor swimming pools, factory halls, etc. The hollow chamber plates used to create such glazing have open ends so that the hollow chambers are in communication with the atmosphere. Although generally the hollow chamber board is mounted in such a way that it is well sealed against dust, dirt, water or insects,
Even in this case, it is not sealed from the atmosphere. The side ends can, for example, be inserted into profiled frames or closed using U-shaped profiled edges.

Eventually, it was discovered that when using hollow chamber plates, condensed water formed in the hollow chambers was a drawback. If such water cannot flow out, it will collect over time in such a quantity that it will fill a significant portion of the cavity. The reason for the formation of condensate is that the plastics used to manufacture the hollow chamber plates, primarily polymethyl methacrylate (RMMA), can absorb small amounts of water (approximately 0.5-1% at average air humidity). I was sent home. Water vapor can also penetrate inside the cavity by diffusion, and this water vapor can separate the condensed water, especially if one outer wall is cooler than the other.

The invention particularly relates to a hollow chamber plate of the above type in which no condensate collection occurs.

At the beginning of West German Utility Model No. 7307322,
Previous attempts to solve the problem of contamination of hollow chambers have been reported. For example, plastic bands are attached to the side edges of hollow profiled boards that form the eaves of a greenhouse. However, in this case, the above-mentioned difficulty of condensed water collection occurs, and this difficulty is solved by cutting the edge of the ventral plate.
It was solved by providing an opening in the belly plate leading to the outside air through which the condensed water could flow out. However, only the lower edge of the eave was always sealed, and the upper edge, covered by the odd-shaped ridge material, remained open.

In order to prevent dust and dirt, and on the other hand to drain condensed water, according to West German Utility Model No. 7307322, U-shaped strips are installed at the side ends of the hollow chamber plates; Grooves in the internal bottom surface of the irregularly shaped plate form an open passage from the hollow chamber to the atmosphere. Also, the pluggable cavity plate closing edge used according to DE 273 087 does not close airtight.

According to DE 25 36 462 A1, after extrusion and elongation, a plastic hollow profile strand stretched by gas pressure is broken up into individual hollow chamber plates periodically using heated welding bits.
At the same time, the ends of the hollow strands in each case are closed in a gas-tight manner, but the closure of the separate hollow chamber ruptures when the weld bit is removed, releasing the pressurized gas enclosed within the hollow chamber. The cavity plate thus has a gas-tight closure at one side end, but communicates with the atmosphere at the other side end.

According to German Patent Application No. 2802179, the hollow chamber plates are heated to a deformation temperature and then in the edge region, in a corresponding pressing device, the cover plates are compressed and deformed so as to form a flange-like edge. By the way,
The cavity board is closed virtually airtight. Although such a closure prevents free gas exchange between the hollow chamber and the ambient atmosphere, it is not airtight in the sense that all ventilation is prevented despite the pressure difference between the hollow chamber and the atmosphere. . Although the lid plate is brought into close contact with the flange-like edge when it is transformed into a flange,
They do not fuse with each other. The contact location is not completely gas-tight, allowing pressure equilibrium if a pressure difference sometimes occurs between the hollow chamber and the atmosphere. Furthermore, the possibility of venting increases if stress tears occur due to deformation of the plate edges after cooling, as usually occurs. These cracks also allow gas to flow in.

The invention is based on the problem of improving the protection of the hollow chamber plate against the formation and collection of condensate and the ingress of dust and dirt.

The solution to this problem was only made possible by a new understanding of condensate formation. New studies have confirmed that the water absorption capacity of plastics, especially PMMA, and the diffusion of water vapor are not the decisive cause of condensate formation, contrary to previously accepted assumptions. Water transport by diffusion alone through the plastic walls of the cavity plate does not, under normal conditions of use, result in harmful condensate collection unless extreme conditions prevail. In general, water that diffuses in will soon escape again. It has been recognized that the primary cause of condensate formation and aggregation is an effect called "breathing". If the hollow chamber has holes, even if small, which open into the atmosphere, air is sucked into the hollow chamber or blown out each time a pressure difference occurs between the gas space of the hollow chamber and the atmosphere. be done. This pressure difference is based on daily fluctuations in atmospheric pressure or changes in the temperature of the air in the cavity. Together with the sucked-in air, a quantity of water vapor corresponding to the particular air humidity is introduced directly into the hollow space, which facilitates the formation of significant amounts of condensed water. Along with the air, extremely fine dust is also drawn in, which along with condensed water can settle on plastic walls and cause harmful contamination over time. The difficulties caused by condensed water therefore cannot be eliminated simply by means of water drainage holes.

The essence of the new recognition on which the invention is based is that if the "breathing" of the cavity is prevented, no harmful condensate collection and ingestion of fine dust will occur. According to the invention, the above-mentioned breathing protection is achieved by completely abandoning the condensate drain, which has hitherto been recognized as indispensable, and by hermetically closing the cavity to the atmosphere. However, the cavities do not have to be closed off tightly from one another. In the spirit of the invention, a cavity is airtight if it has no free openings to the atmosphere. Some aeration due to diffusion is not taken into account. Of course, the hollow space is also watertight and dusttight in this case.

The hollow-chamber plates produced according to the invention are suitable for all applications for which hollow-chamber plates with open or non-hermetically closed cavities were used up to now. Dust elimination is an advantage, making it effective even for indoor applications or use in completely dry environments. Reducing condensate formation and avoiding condensate collections containing dirt is advantageous in all applications where hollow chamber plates isolate spaces from different temperatures and/or humidity.

Therefore, the hollow chamber board is suitable as roofing material, glazing material and wall material for temperature control, indoor swimming pools, gymnasiums, workplaces, station halls, warehouses, etc.

Next, the present invention will be explained by examples. In the method according to the invention, starting from a hollow profiled plate with an open side end, this plate can be closed individually at both ends. Preferably, the closing of the hollow space is comprised immediately after extrusion in the division of the continuously extruded hollow strand into individual plates. In this case, the strand is split and the resulting ends are closed in an airtight manner in the same working step.

Typical hollow chamber plates according to Figure 1 have a thickness of 3 to 60 mm.
mm, preferably 10 to 20 mm, and thickness 0.5 to 3 mm
It has an outer wall of The hollow space 4 has a generally rectangular cross section. For typical plate widths of 1000 to 2000 mm, the cavity plate has 20 to 100 cavities arranged side by side.

Subsequent closure of the open end Prefabricated plastic membrane 5 according to FIG.
It is welded onto the open end of the hollow chamber 4 at both ends.
This bond can be made by heating the plastic band 5 (preferably made of the same plastic as the plate) and the side edges of the plate to a thermoplastic state and bonding under pressure. The side protrusions 11 are used as drop edges.

It is simple and advantageous to heat a portion approximately 10 to 20 mm wide along the side edges to a thermoplastic state, and then use both side plates to compress the outer walls 1 and 2 and fuse them together. In this case the ventral panels 3 are compressed together and fused with the material of the outer walls 1, 2. In this way, a closed shape as shown in FIGS. 3-7 is obtained. The weld seam 6 can be present in the central plane of the plate, as in FIG. 3, or on one side, for example in the outer wall 1, as in FIG.
may exist on the surface. For installation,
It is advantageous if the closure 6 obtained by welding has a surface 7 parallel to the outer wall, which is easily produced by a correspondingly formed weld bit.

If the weld seam according to FIG. 3 can still be thermoformed, it can also be compressed in the direction of the plate using a hot pressing tool according to FIG. 6 to produce an enlarged support surface.

Extended bearing surfaces or end surfaces are advantageous if considerable forces, for example the self-weight of a vertically standing high plate section, act on them. It is advantageous if the support surface 9, which is perpendicular to the plane of the outer walls 1, 2, has a width b of at least half the thickness of the plate. According to FIG. 5, this is achieved by a correspondingly designed lip 8. This edge can be produced by thermoplastic deformation of a compressed plate edge between two correspondingly shaped press tools. Such edge formation also satisfies the purpose of the drop edge.

Instead of a continuous support surface as in FIGS. 2 and 5, it is also arranged in one plane perpendicular to the plane of the outer wall,
A better distribution of forces is also obtained with several edges 10, which are preferably spaced apart by a distance b of at least half the plate thickness. This can be obtained not only in the shape shown in Fig. 6 but also in the case of the shape shown in Fig. 7.
In this case, the welding is not done at the outermost plate edge;
Since it is done in the area close to the edge, the original profile is still obtained at the outer edge.

In the case of the welded closure method, the hollow chamber is at least
It is used to form a closure, which closes when the hollow chamber plate becomes thermoplastic in the deformed part. The two outer walls 1, 2 are hermetically welded to each other or over the side edges using plastic bands which are also in the thermoplastic state. In this sense, a plastic material can be considered thermoplastic when the plastic parts that are contacted are welded together under pressure to form a continuous adhesive bond. This shows that, in general, no reflection of light occurs at the interface.

Welding with side plates compressing both outer walls, including the belly plate present between them, or crimping bands to the side edges, is particularly useful for relatively thick walls made of limited impact resistant plastics such as PMMA. In the case of a part,
Stresses develop within the plastic material. Such stress can cause unfavorable “breathing” by breaking the airtight closure.
It was confirmed that fissures were formed that caused a series of ruptures. According to a preferred embodiment of the invention, these disadvantages are overcome when the closure 6 and the plate area adjacent thereto, which are formed in the thermoplastic state, are heated from a temperature 10° below the Vicat softening temperature of the plastic material of the cavity plate. This is avoided by maintaining the temperature in the range up to 20° above that temperature for at least 1 minute, preferably from 5 to 15 minutes. The higher the temperature, the shorter the heating time can be.
For the upper limit of the temperature range, 1 to 2 minutes is sufficient, and for the lower limit, 15 minutes or more is required. When there is a risk of deformation, the Vicat softening temperature must not be exceeded by more than 10° to 12°. In the case of PMMA, the advantageous temperature range for the afterheating is between 110 DEG and 130 DEG C., and the heating time can be between 5 and 15 minutes. At 120° C., a treatment time of 10 minutes is advantageous.

Hollow chamber closure in the case of extrusion method Hollow chamber closure involves separating a section of desired length from the continuously produced hollow profile strand using an extrusion method for continuously producing hollow profile strands. , can be included in the extrusion method for continuous production of hollow profiled strands in that the end faces occurring at both ends of the separation location are closed in the same working step. This takes place at the extrusion device, where the strands have already been cooled to a temperature below their softening temperature. The strand which is continuously extruded forward is closed at its front end, so that during extrusion the hollow chamber is filled with air or other inert gas by means of a conduit passing through the mandrel of the extrusion die forming the hollow chamber. There must be.

This gas can be introduced with a slight overpressure in order to press down the hollow strand in a plastic state. In this case, it is possible to work with the forming tube without vacuum. Since separating and closing the strands requires a certain period of time during which the strands are continuously extruded, a separating and closing device, preferably operating fully automatically, moves the strands together with the extrusion speed by means of guiding elements. guided and returned to the next separation position of the strand after the end of the working process.

The separating and closing device may consist, for example, of a saw, a heating device and a pressing device. The saw cuts the desired length from the hollow strand with a cut extending transversely to the extrusion device. The two resulting cuts and the two plastic bands suitable for side edge closure are heated to a thermoplastic state using a heating device and each one is pressed using a pressing device.
bands are welded to the side edges.

Another closure device is illustrated in FIG. The device is rigidly clamped to a hollow strand which is moved continuously in the direction of the arrow in a roller path 27 with a hydraulically driven jaw 20 and thereby moved together by a rail 22 with rollers 21. The heat sink 23 heats the deformed portion of the hollow strand until it becomes thermoplastic. Once this is achieved, the heated separating and welding bit 24 is stretched by water pressure until the cutting edge contacts the middle of the strand. After the bit 24 is restored, the radiator 23 continues to irradiate at a reduced power to post-heat the weld location and relieve internal stress. The cut-out airtight closing cavity plate 26 is then removed, the clamping jaw 20 is loosened and the closing device is transported back on the rail 22 to the next separating position.

If the reheating time required for stress relief is longer than the working cycle time during which the plate of the respective desired length is extruded, the reheating must be carried out using a separate device. For example, a tunnel heating device of sufficient length in which the entire plate is heated is suitable. The individual radiators are also operated together with the strand edge and the cut-out plate in the closing position 6, with several radiators being movable on rails or suspended from the chain in the extrusion channel. located along. The heat sinks are connected to each other at regular intervals corresponding to the length of the plate, and can be returned to their original position by the length of the plate after each working cycle.

The different edge geometries according to FIGS. 4 to 7 can be produced in series using correspondingly designed separation and welding bits. For the production of the edge profile according to FIG. 4, a welding bit, preferably acting from one side on a heated fixture, suffices. 7th
The edge shape shown has two parallel weld bits, but can be manufactured using a tool without cutting edges 25. Between the two weld bits a bulge with a short closed chamber is created. This bulge is cut with a saw after post-heating and cooling. The edge shape according to FIG. 5 can be produced from the edge according to FIG. 4 with a surface 7 of corresponding length by bending the surface 7, still in a softened state, with an auxiliary tool to form a drop edge 8. The edge shape according to FIG. 6 can be produced from the edge shape according to FIG. 3 by crushing in the softened state, but auxiliary tools are likewise required for this purpose.

[Brief explanation of the drawing]

FIG. 1 is a front view of the unclosed end of a typical cavity plate closable according to the present invention, and FIGS. 2-7 are longitudinal sectional views of various embodiments of the closed end of the cavity plate. , FIG. 8 is a schematic cross-sectional view of an apparatus for carrying out the method of the invention. 1, 2...outer wall, 3...abdominal plate, 4...hollow chamber,
6... Welding seam (closed part), 7... Surface parallel to the outer wall, 12... Separation position, 20... Clamp jaw, 21... Roller, 22... Rail, 23...
... Heat sink, 24 ... Separation and welding bit.

Claims (1)

[Claims] 1. Two generally flat and parallel outer walls;
Starting from an integrally extruded hollow profile plate consisting of a belly plate arranged between the two outer walls, a hollow chamber plate made of extruded plastic with a number of hollow chambers contained between the two outer walls and the belly plate; In producing a hermetically closed hollow chamber plate by heating to the deformation temperature in at least a partial region and closing the hollow chamber in the heated region, the hollow chamber plate is heated to the deformation temperature at least in the region used for the closure to be produced. from an extruded plastic, characterized in that it is heated to a thermoplastic state over a temperature range of 100 to 100 mm, and in the thermoplastic region of the hollow chamber plate the two outer walls are hermetically welded to each other or by means of a thermoplastic band covering the side edges. A method for manufacturing an airtight closed hollow chamber plate comprising: 2. The closure 6 made in the thermoplastic state is maintained for at least 1 minute at a temperature ranging from 10° below the Vicat softening temperature of the plastic material of the hollow chamber plate to 20° above the softening temperature. A method according to claim 1. 3. A method as claimed in claim 2, in which the hollow chamber plate is moved through a heated tunnel at the speed at which it is extruded. 4. A method as claimed in claim 2, in which the hollow chamber plate is moved with the speed with which it is extruded and, at the same time, the heating device is jointly operated in the region of the closure. 5. The method as claimed in claim 1, wherein the outer walls 1, 2 are compressed airtight in a closed region in a thermoplastic state with the formation of a surface 7 parallel to the outer walls. 6. A method as claimed in claim 5, in which the outer wall is compressed in such a way that deep grooves or separation locations 12 are formed in the surface 7.